Magnetic recording medium

Abstract

Provided is a magnetic recording medium having high C/N, low error rate, and excellent running durability. The magnetic recording medium comprises a magnetic layer 1 comprising a ferromagnetic powder and a binder, or comprising a nonmagnetic layer comprising a nonmagnetic powder and a binder and a magnetic layer 2 comprising a ferromagnetic powder and a binder in this order on a nonmagnetic support. An undercoating layer comprising a clay mineral coated with an organic compound and a binder is comprised between the nonmagnetic support and the magnetic layer 1 or between the nonmagnetic support and the nonmagnetic layer, as well as said clay mineral coated with an organic compound has a thickness ranging from 0.5 to 5 nm and an aspect ratio ranging from 50 to 10,000.

1. A magnetic recording medium comprising a magnetic layer  1  comprising a ferromagnetic powder and a binder, or comprising a nonmagnetic layer comprising a nonmagnetic powder and a binder and a magnetic layer  2  comprising a ferromagnetic powder and a binder in this order on a nonmagnetic support, wherein
 an undercoating layer comprising a clay mineral coated with an organic compound and a binder is comprised between the nonmagnetic support and the magnetic layer  1  or between the nonmagnetic support and the nonmagnetic layer, as well as  
 said clay mineral coated with an organic compound has a thickness ranging from 0.5 to 5 nm and an aspect ratio ranging from 50 to 10,000.  
 
     
     
       2. The magnetic recording medium according to  claim 1 , wherein said binder comprised in the undercoating layer is prepared from a starting material in the form of a radiation-curable compound, and prepared by curing said radiation-curable compound by irradiation. 
     
     
       3. The magnetic recording medium according to  claim 1 , wherein said undercoating layer has a thickness ranging from 0.3 to 3 μm. 
     
     
       4. The magnetic recording medium according to  claim 1 , wherein said ferromagnetic powder is a ferromagnetic hexagonal ferrite powder having an average plate diameter ranging from 5 to 40 nm or a ferromagnetic metal powder having an average major axis length ranging from 20 to 100 nm. 
     
     
       5. The magnetic recording medium according to  claim 1 , wherein said clay mineral is a layered silicate compound. 
     
     
       6. The magnetic recording medium according to  claim 5 , wherein said layered silicate compound is at least one member selected from the group consisting of smectite clay, swelling mica, and swelling vermiculite. 
     
     
       7. The magnetic recording medium according to  claim 5 , wherein said layered silicate compound is montmorillonite, beidellite, nontronite, saponite, iron saponite, hectorite, sorconite, stibnite, bentonite, substitution products thereof, derivatives thereof, or mixtures thereof. 
     
     
       8. The magnetic recording medium according to  claim 5 , wherein said layered silicate compound is Li-type tenorite, Na-type tenorite, Li-type tetrasilicon mica, and Na-type tetrasilicon mica, substitution products thereof, derivatives thereof, or mixtures thereof. 
     
     
       9. The magnetic recording medium according to  claim 1 , wherein said said clay mineral coated with an organic compound is a compound obtained by subjecting a layered silicate compound to the action of organic onium ions. 
     
     
       10. A method of reproduction with a magnetoresistive (MR) head, wherein the reproduction is conducted on the magnetic recording medium according to  claim 1 .